Map-based cloning of the susceptibility locus conditioning bs6 resistance in pepper (Capsicum annuum L.) encoding mutant alleles of pseudokinase proteins.
4 affiliations
- 1Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi A. u. 4., Gödöllő, 2100, Hungary.
- 2Institute of Plant Biology, HUN-REN Biological Research Centre, Szeged, Hungary.
- 3AMBIS Biotechnology Research and Development Ltd., Budapest, Hungary.
- 4Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi A. u. 4., Gödöllő, 2100, Hungary. [email protected].
Abstract
Key message
The bs6 resistance gene against bacterial spot was identified by map-based cloning in pepper (C. annuum L.). The recessive bs6⁶¹ locus of pepper Capsicum annuum L. var. 61R (Ca61R) conditions a non-hypersensitive resistance trait, characterized by a slightly swollen, pale green, photosynthetically active leaf tissue, following Xanthomonas euvesicatoria Race 6 (XeR6) infection. In contrast, C. annuum cv. Feherozon (CaFo) is susceptible to XeR6. Map-based cloning of the bs6⁶¹ locus revealed that the bs6⁶¹ locus encodes three predicted proteins, pbs6⁶¹npk, pbs6⁶¹n, pbs6⁶¹pk in Ca61R which are the counterpart of the three wild type predicted proteins, pBs6FoNPK, pBs6FoN and pBs6FoPK in CaFo, respectively. Sequence analysis revealed that the pBs6FoNPK protein showed 35% identity and 53% similarity to the ZRK4 pseudokinase (pAtZRK4) identified in Arabidopsis thaliana, which possesses N-terminal and C-terminal (pseudokinase) domains. The pBs6FoN and pBs6FoPK proteins resemble the N-terminal and C-terminal domains of the pBs6FoNPK protein, respectively, thus, they also contain pseudokinase domains/sequences. In Ca61R, pbs6⁶¹npk and pbs6⁶¹n are truncated counterparts of pBs6FoNPK and pBs6FoN, respectively, as a consequence of a single-nucleotide insertion that causes frameshifts and premature stop codons, whereas pbs6⁶¹pk differs from pBs6FoPK by a single amino acid, a serine to alanine substitution at position 133. These three proteins are considered functionless. The ORF of pBs6FoN, pBs6FoPK and pbs6⁶¹n, pbs6⁶¹pk, respectively, are encoded by a single transcript in both parental plants. For this reason the translation of pBs6FoPK was ambiguous, however, the expression of pBs6FoN-dsRed fusion protein demonstrated that pBs6FoPK in fact can be translated. The three wild type proteins (pBs6FoNPK, pBs6FoN and pBs6FoPK) were independently responsible for ETS (effector-triggered susceptibility), because all three genes had to be in mutant configuration to manifest the resistant phenotype, in addition, any one of the three was able to reverse the resistant phenotype to susceptibility. Functional analysis using virus-induced gene silencing and transient genetic complementation demonstrated that the three CaFo proteins contribute redundantly to XeR6 susceptibility. Silencing either Bs6FoNPK, Bs6FoN and Bs6FoPK alone did not alter susceptibility, whereas simultaneous silencing of these genes conferred resistance. Conversely, the individual expression of pBs6FoNPK, pBs6FoN, and pBs6FoPK, in the resistant Ca61R background each restored susceptibility. These results demonstrate that the three Bs6 proteins act redundantly to promote XeR6 susceptibility and that loss of function of all three corresponding proteins was required for the recessive resistance phenotype conferred by bs6⁶¹.
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BibTeX
@article{toth2026mapbased,
title = {{Map-based cloning of the susceptibility locus conditioning bs6 resistance in pepper (Capsicum annuum L.) encoding mutant alleles of pseudokinase proteins.}},
author = {Zoltan Toth and Zoltan Gabor Toth and Peter Kalo and Gyorgy B Kiss and Zoltan Szabo},
journal = {TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik},
year = {2026},
month = oct,
doi = {10.1007/s00122-026-05407-2},
url = {https://europepmc.org/article/MED/42900360},
note = {CC BY},
}
RIS
TY - JOUR
TI - Map-based cloning of the susceptibility locus conditioning bs6 resistance in pepper (Capsicum annuum L.) encoding mutant alleles of pseudokinase proteins.
AU - Zoltan Toth
AU - Zoltan Gabor Toth
AU - Peter Kalo
AU - Gyorgy B Kiss
AU - Zoltan Szabo
PY - 2026
DA - 2026/10/20
JO - TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik
DO - 10.1007/s00122-026-05407-2
UR - https://europepmc.org/article/MED/42900360
AB - Key message The bs6 resistance gene against bacterial spot was identified by map-based cloning in pepper (C. annuum L.). The recessive bs6⁶¹ locus of pepper Capsicum annuum L. var. 61R (Ca61R) conditions a non-hypersensitive resistance trait, characterized by a slightly swollen, pale green, photosynthetically active leaf tissue, following Xanthomonas euvesicatoria Race 6 (XeR6) infection. In contrast, C. annuum cv. Feherozon (CaFo) is susceptible to XeR6. Map-based cloning of the bs6⁶¹ locus revealed that the bs6⁶¹ locus encodes three predicted proteins, pbs6⁶¹npk, pbs6⁶¹n, pbs6⁶¹pk in Ca61R which are the counterpart of the three wild type predicted proteins, pBs6FoNPK, pBs6FoN and pBs6FoPK in CaFo, respectively. Sequence analysis revealed that the pBs6FoNPK protein showed 35% identity and 53% similarity to the ZRK4 pseudokinase (pAtZRK4) identified in Arabidopsis thaliana, which possesses N-terminal and C-terminal (pseudokinase) domains. The pBs6FoN and pBs6FoPK proteins resemble the N-terminal and C-terminal domains of the pBs6FoNPK protein, respectively, thus, they also contain pseudokinase domains/sequences. In Ca61R, pbs6⁶¹npk and pbs6⁶¹n are truncated counterparts of pBs6FoNPK and pBs6FoN, respectively, as a consequence of a single-nucleotide insertion that causes frameshifts and premature stop codons, whereas pbs6⁶¹pk differs from pBs6FoPK by a single amino acid, a serine to alanine substitution at position 133. These three proteins are considered functionless. The ORF of pBs6FoN, pBs6FoPK and pbs6⁶¹n, pbs6⁶¹pk, respectively, are encoded by a single transcript in both parental plants. For this reason the translation of pBs6FoPK was ambiguous, however, the expression of pBs6FoN-dsRed fusion protein demonstrated that pBs6FoPK in fact can be translated. The three wild type proteins (pBs6FoNPK, pBs6FoN and pBs6FoPK) were independently responsible for ETS (effector-triggered susceptibility), because all three genes had to be in mutant configuration to manifest the resistant phenotype, in addition, any one of the three was able to reverse the resistant phenotype to susceptibility. Functional analysis using virus-induced gene silencing and transient genetic complementation demonstrated that the three CaFo proteins contribute redundantly to XeR6 susceptibility. Silencing either Bs6FoNPK, Bs6FoN and Bs6FoPK alone did not alter susceptibility, whereas simultaneous silencing of these genes conferred resistance. Conversely, the individual expression of pBs6FoNPK, pBs6FoN, and pBs6FoPK, in the resistant Ca61R background each restored susceptibility. These results demonstrate that the three Bs6 proteins act redundantly to promote XeR6 susceptibility and that loss of function of all three corresponding proteins was required for the recessive resistance phenotype conferred by bs6⁶¹.
SN - 1432-2242
ER -